Is this likely to pose problems during my travel, like at the London Heathrow Airport?
No. Consider if your flight was from Singapore via New Delhi. At LHR, New Delhi is still where you arrived from (directly).
Security, Immigration, Customs, airline staff, shopkeepers, taxi drivers etc don't really care where you came from, though they may ask. And, if it were possible, the same people would care even less where your visa was issued.